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A new way to disinfect water efficiently and cost-effectively

Kemira has developed a unique water treatment solution that is both sustainable and highly efficient: DesinFix. One of the first places to have trialled the new technology is Frankfurt, Germany’s fifth-largest city.

Frankfurt’s two wastewater treatment plants and one sludge treatment plant handle wastewater from both Frankfurt itself, a city of 672,000 people, and a number of adjacent municipalities in the Frankfurt/Rhine-Main metropolitan region, home to some 5.6 million people. All of which makes the scale of the treatment challenges facing the city quite daunting.

Kemira’s DesinFix has been developed to meet disinfection needs related to the reuse of water in applications such as irrigation, recreational use, and industry.

One of the city’s treatment plants, the Sindlingen facility, began testing a new disinfection method developed by Kemira – DesinFix – to improve its performance and as a potential replacement for chlorine dioxide in spring 2010. The initial aim was to generate service water clean enough for off-gas scrubbing and diluting polymers, both processes that call for huge amounts of water and represent ideal opportunities for improving water use efficiency.

During the trial, the city decided to up the ante and set the required level of disinfection to match the EU’s upcoming bathing directive. Although the directive only applies to outgoing water, the city reasoned that it represents a reasonable target for internal process water as well.

In practice, the city’s goal is to reduce the levels of Enterococci and E. coli bacteria to the levels required in the new directive.

Safe and versatile

The heart of the DesinFix system, DEX-135®, is produced on-site in a process that generates only two by-products: water and carbon dioxide.

As elsewhere, the results of the Frankfurt trial confirmed that DEX-135 destroys Enterococci and E. coli very effectively, even more effectively than chlorine dioxide in fact. It costs less as well. DesinFix also has other two advantages over chlorine: it does not increase water salt content and is less corrosive. The DesinFix system is also easy to install and can be used wherever water needs to be disinfected.

Although the Sindlingen wastewater treatment plant does not need to meet the requirements of the EU’s new bathing water directive, which will come into effect in 2015, the results of the trial show that the dosages used in the DesinFix system are more than sufficient to make water suitable for bathing.

Long-term results from other plants confirm that the requirements of the directive can be met very reliably using the new technology, which means that it could prove very useful in treating the large volumes of wastewater that municipalities everywhere are faced with before returning water to rivers and lakes.

Frankfurt is one of the cities to have found that DesinFix offers multiple benefits over other forms of disinfection. Photo courtesy of Thomas Wolf.

Chlorine-free disinfection

Kemira’s DesinFix is a complete solution including chemicals, equipment, and related services, and has been developed to meet disinfection needs related to the reuse of water in applications such as irrigation, recreational use, and industry.

DesinFix contains a highly efficient mixture of formic acid and hydrogen peroxide. Mixed together, these create a highly efficient biocide, DEX-135. The latter forms hydroxyl radicals, which kill bacteria. Measurements have shown that up to a 6 log (99.9999%) kill ratio can be achieved using a DesinFix solution.

DEX-135 takes only 10 minutes to disinfect water, and can no longer be detected an hour after dosing, as it breaks down into CO2 and water, releasing no toxic by-products.

Kemira has R&D centres in Finland, China, the US, and Brazil, and employs some 450 people in research. Other recent R&D success stories in addition to DesinFix® include H2S-Guard™ for dealing with odour and corrosion problems related to hydrogen sulphide; LumiKem®, a monitoring process that helps paper mills optimise their wastewater treatment; FennoClean D, for controlling biofilm oxidising biocides; and KemGuard® polymers.

DesinFix also offers low energy consumption, competitive operating costs, minimal maintenance requirements, and a much lower investment cost compared to UV-light or ozone disinfection.

Water is the connection

Kemira is a global €2 billion chemicals company focused on serving customers in water-intensive industries. The company offers water quality and quantity management that improves customers’ energy, water, and raw material efficiency. Kemira’s goal is to be a leading water chemistry company.

Kemira’s Municipal & Industrial segment offers services for municipal and industrial water treatment, covering multiple applications – from chemical coagulation and precipitation to biological treatment support, odour and corrosion control, disinfection, and sludge treatment.

“A complete wastewater disinfection technology 
for water reuse applications.”

> Steve Laborda
(Published in HighTech Finland 2011)